--- a/clash-lib.cabal
+++ b/clash-lib.cabal
@@ -380,7 +380,7 @@ test-suite doctests
     build-depends:
       base,
       clash-lib,
-      doctest-parallel >= 0.2 && < 0.4,
+      doctest-parallel >= 0.2 && < 0.5,
       filepath
 
 test-suite unittests
